$ -2.16\% \div 9\% $
Solution: Convert each percentage into a decimal dividing by $100$ $ -0.0216 \div 0.09 $ ${0}$ ${0}$ ${9}$ ${2}$ ${1}$ ${6}$ ${0}$ $\text{Shift the decimal 2 to the right.}$ ${2}$ $\text{How many times does }9\text{ go into }{2}\text{?}$ ${0}$ ${0}$ ${2}$ $-\vphantom{0}$ ${2}\div9={0}\text{ or }9\times{0} = {0}$ ${1}$ $\text{How many times does }9\text{ go into }{21}\text{?}$ ${2}$ ${1}$ ${8}$ ${3}$ $-\vphantom{0}$ ${21}\div9={2}\text{ or }9\times{2} = {18}$ ${6}$ $\text{How many times does }9\text{ go into }{36}\text{?}$ ${4}$ ${3}$ ${6}$ ${0}$ $-\vphantom{0}$ ${36}\div9={4}\text{ or }9\times{4} = {36}$ ${0}$ $\text{How many times does }9\text{ go into }{0}\text{?}$ ${0}$ ${0}$ ${0}$ $-\vphantom{0}$ ${0}\div9={0}\text{ or }9\times{0} = {0}$ A negative number divided by a positive number is a negative number. $-0.0216 \div 0.09 = -0.24$ Convert the decimal into a percentage by multiplying by $100$. $-0.24 = -24\%$